The purpose of this study is to investigate if 28 days of treatment with AZD2066 compared to placebo can relieve the pain arising from the nervous system when the patients are touched by something that should not cause pain or have severe pain when they are touched by something that should only cause a little pain.

Change in Mean Numerical Rating Scale (NRS) Pain Score From Baseline to Last 5 Days on Treatment [ Time Frame: Change in mean pain intensity from 5-day baseline to the last 5 days on treatment, measure twice daily with NRS (12-hour recall) ] [ Designated as safety issue: No ]

Mean pain intensity for 5-day baseline period (morning Day -5 to evening Day-1) and mean pain intensity for last 5 days on treatment (ie, last dose day and the 4 preceding calendar days) was calculated based on the NRS scale (0-10). 0=No pain, 10=Worst pain imaginable.

Secondary Outcome Measures:

Patients With ≥30% Reduction From Baseline in NRS Pain Intensity Score (Responder Rate) at Day 28 [ Time Frame: 28 days ] [ Designated as safety issue: No ]

Patients With Patient Global Impression of Change (PGIC) Score of at Least "Much Improved" (Responder Rate) at Day 28 [ Time Frame: 28 days ] [ Designated as safety issue: No ]

PGIC scale ranges from 1-7 where 1=Very much improved and 7=Very much worse Responder=Patient with a response of " much improved" or "very much improved" Responder rate=(no. of responders/total no. of patients)*100

Change in Short Form McGill Pain Questionnaire (SF-MPQ) Sensory Index From Baseline to Day 28 [ Time Frame: 28 days ] [ Designated as safety issue: No ]

Sensory index=sum of the intensity scale values of the words chosen for the descriptors 1-11 in the questionnaire. Range of scores for the sensory index=0-33 (higher score represents a worse condition).

Change from baseline (measured prior to randomization) to Day 28 was calculated.

Change in SF-MPQ Affective Index From Baseline to Day 28 [ Time Frame: 28 days ] [ Designated as safety issue: No ]

Affective index=sum of the intensity scale values of the words chosen for the descriptors 12-15 in the questionnaire. Range of scores for the affective index=0-12 (higher score represents a worse condition).

Change from baseline (measured prior to randomization) to Day 28 was calculated.

Change in Brief Pain Inventory-Short Form (BPI-SF) Pain Severity From Baseline to Day 28 [ Time Frame: 28 days ] [ Designated as safety issue: No ]

Change from baseline (measured prior to randomization) to Day 28 was calculated for the pain severity (mean of 4 intensity items). Each intensity item is recorded on a NRS 0-10, where 0=No Pain and 10=Pain as bad as you can imagine.

Change in BPI-SF Pain Interference From Baseline to Day 28 [ Time Frame: 28 days ] [ Designated as safety issue: No ]

Change from baseline (measured prior to randomization) to Day 28 was calculated for pain interference (mean of 7 interference items). Each interference item is recorded on a NRS 0-10, where 0=No interference and 10=Interferes completely.

Painful symptoms due to neuropathic pain for a period of 3 months to 5 years, associated with mechanical allodynia and/or punctate hyperalgesia.

Exclusion Criteria:

Other pain that may confound assessment of neuropathic pain.

Diagnosis of any severe neurological disease.

History of significant psychiatric disease/condition and/or history of psychotic disorders among first degree relatives.

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Please refer to this study by its ClinicalTrials.gov identifier: NCT00939094